Testing randomness functions

[enderNakamoto]

Discord user ID

enderwiggins

Describe your question in detail.

What is a good way to test randomness functions? I am getting this weird error, and I do not understand why:

In my module I have :

#[randomness]
    entry fun attack_with_randomness(attacker: &signer) acquires PlayerState, GameState {
        .....
        let random_bonus = randomness::u64_range(0, MAX_RANDOM_MODIFIER);
        ....
        
        }
        
         #[test_only]
        #[lint::allow_unsafe_randomness]
        public fun attack_with_randomness_for_test(attacker: &signer) acquires PlayerState, GameState {
            attack_with_randomness(attacker);
        }
    
    ```
    
    In the tests, I am calling warlords::attack_with_randomness_for_test(&sender); 
    

    

[adipundir]

I am facing the same issue.

[Tlazypanda]

gm gm @enderNakamoto @adipundir this error suggests that the PerBlockRandomness resource is not under the module for testing which is the case. So for tests we have a function called initialize_for_testing that sets the seed and creates this resource.

From randomness.move core file

 /// Must be called in tests to initialize the PerBlockRandomness resource.
public fun initialize(framework: &signer) {
        system_addresses::assert_aptos_framework(framework);
        if (!exists<PerBlockRandomness>(@aptos_framework)) {
            move_to(framework, PerBlockRandomness {
                epoch: 0,
                round: 0,
                seed: option::none(),
            });
        }
    }

    #[test_only]
    public fun initialize_for_testing(framework: &signer) acquires  PerBlockRandomness {
        initialize(framework);
        set_seed(x"0000000000000000000000000000000000000000000000000000000000000000");
    }

Usage in your test - This is a sample test from the Aptogotchi.move randomisation code example - complete reference: https://github.com/aptos-labs/aptogotchi-random-mint/blob/main/move/sources/aptogotchi.move

    // ==== TESTS ====
    // Setup testing environment
    #[test_only]
    use aptos_framework::account::create_account_for_test;
    #[test_only]
    use aptos_std::crypto_algebra::enable_cryptography_algebra_natives;

    #[test_only]
    fun setup_test(
        fx: &signer,
        account: &signer,
        creator: &signer,
    ) {
        enable_cryptography_algebra_natives(fx);
        randomness::initialize_for_testing(fx);
        randomness::set_seed(x"0000000000000000000000000000000000000000000000000000000000000000");

        // create a fake account (only for testing purposes)
        create_account_for_test(address_of(creator));
        create_account_for_test(address_of(account));

        init_module(account)
    }